БЪЛГАРСКО ГЕОЛОГИЧЕСКО ДРУЖЕСТВО, Национална конференция с международно участие „ГЕОНАУКИ 2017“ BULGARIAN GEOLOGICAL SOCIETY, National Conference with international participation “GEOSCIENCES 2017”

First data for mineral of group from Zvezdel, Eastern Rhodopes, Bulgaria Първи данни за минерал от групата на девилина от Звездел, Източни Родопи, България Zlatka Delcheva, Yana Tzvetanova, Nadia Petrova, Elena Tacheva, Rositsa Nikolova Златка Делчева, Яна Цветанова, Надя Петрова, Елена Тачева, Росица Николова

Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 107, 1113 Sofia; E-mail: [email protected]

Keywords: devilline group mineral, Cu/Zn ratio, , Zvezdel area.

Introduction The sample used in this study is deposited in the mineral collection of the Institute of Mineralogy and Crystallography, Bulgarian Academy of Sciences. This mineral specimen, donated by Velichko Krastev, has been found in the oxidized zone of the epither- mal Zvezdel deposit belonging to Zvezdel-Pcheloyad ore field, which is situated in the Eastern Rhodopes Paleogene depression, SE Bulgaria (Nedialkov, Mav­ roudchiev, 1995). Initially, this sample was recog- nized as serpierite. The serpierite is hydrated copper sulfate, Ca(Cu,Zn)4(OH)6(SO4)2·3H2O from devilline group, first described in the mines of Laurion (Greece). The crystal structure analysis of the mineral has been made by Sabelli and Zanazzi (1968). Fig. 1. Mineral association of the studied sample Devilline group minerals from Bulgarian localities have not been characterized until now. The purpose of this study is to obtain crystal chemical and structural data of such kind of mineral. of the sample containing DGM, , and calcite are presented on Figure 2. Microscopically, un- der SEM (Fig. 3), the DGM shows radial aggregates Methods of elongated [010] lathlike crystals. The chemical The sample was studied under: (i) X-ray powder analysis shows the presence of SO3 (32.25 wt%), CaO diffractometer D2 Phaser Brucker AXS with Cu ra- (8.95 wt%), CuO (49.73 wt%) and ZnO (9.07 wt%), diation; (ii) scanning electron microscopy (SEM) and that means a Cu/Zn ratio of 5.7 for our DGM sample, electron probe microanalysis: ZEISS SEM EVO 25 while for the serpierite (Sabelli, Zanazzi, 1968) this LS – EDAX Trident at acceleration voltage of 20 kV ratio is 1.9. and (iii) X-ray single crystal diffractometer Supernova A, The single crystal analysis shows that DGM is Oxford diffraction, Mo-radiation. monoclinic with lattice parameters: a=18.41(2), b=6.22(1), c=12.09(1) Å, β=90.781° and a I2, whereas the crystal structure of the serpierite Results has been solved by Sabelli and Zanazzi (1968) with The studied sample contains devilline group mineral a space group C2/c and lattice parameters: a=22.186, (DGM), gypsum, dolomite, , , chal- b=6.250, c=21.853 A, β=113.36°. The obtained lat- copyrite, quartz and calcite (Fig. 1). Macroscopically, tice parameters and space group differ as well from the DGM forms greenish blue crusts covering tiny that of other devilline group minerals such as devilline gypsum crystals. X-ray powder diffraction patterns (Sabelli, Zanazzi, 1972).

19 Fig. 2. X-ray powder diffraction patterns of the sample containing DGM, gypsum, quartz and calcite

Fig. 3. SEM images of DGM

Fig. 4. Unit cell of DGM (black line) and serpierite (Sabelli, Zanazzi, 1968 – red dotted line) and next to it Cu, Zn octa- hedron decorated sheet

Both the unit cell of DGM (black line) and the a structural topology comprises [Cu4Zn1(SO4)4(O or serpierite (Sabelli, Zanazzi, 1968) (red dotted line) OH)12] decorated sheets. and Cu, Zn octahedron decorated sheet are shown on (iv) The position of Zn atoms within the sheet was Figure 4. The cation octahedron coordination in the specified and it was found that unlike the Cu atoms, sheet is as follows: CuO5O1(SO4), CuO4O2(SO4) the Zn ones are not coordinated by oxygen atoms from and ZnO6 with distances Cu–O: 1.90–2.5Å and Zn–O: SO4 groups. 2.11–2.14 Å, respectively. References Conclusions Nedialkov, R., B. Mavroudchiev. 1995. Geochemical and (i) The present study reports for the first time morpho- mineralogical peculiarities of the Zvezdel pluton (East logical, chemical and structural data of devilline group Rhodopes, Bulgaria). – In: Proceedings of the XV Congress mineral found in Bulgarian locality. of the Carpatho-Balcan Geological Association. Geol. (ii) The crystal structure of mineral under study was Soc. Greece, Sp. Publ., No 4/2. September 17–20, Athens, Greece, 561–565. described in space group I2 with a cell volume twice as Sabelli, C., P. F. Zanazzi. 1968. The crystal structure of ser- small as that of the serpierite (Sabeli, Zanassi, 1968). pierite. – Acta Crystalographica, B24, 1214–1221. (iii) Single crystal diffraction data show that the studied Sabelli, C., P. Zanazzi. 1972. The crystal structure of devillite. material belongs to the devilline group minerals which – Acta Crystalographica, B28, 1182–1189.

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